Sure. There are often fanfictions that focus on the unique dynamic between Zed and Bucky in the Zombies universe. Check out some of the more popular fanfiction platforms like FanFiction.net as well. A lot of the stories might delve into their backstories and how they came to be the characters we know in relation to each other. Maybe a story where Zed has to protect Bucky from a new threat in their zombified world.
Well, I haven't read every Zombies Zed x Bucky fanfiction out there, but I do know that Tumblr can also be a source for some fan - created content. Some fanfictions might play with the idea of Zed and Bucky having different personalities than what we see in the official material. For example, a story where Bucky is more outgoing and Zed is more reserved, and how they overcome their differences while dealing with the zombie - related chaos around them.